Opening ATTACHMENT Files

The ATTACHMENT file type is primarily associated with Microsoft Outlook.

ATTACHMENT	File extension: ATTACHMENT
	File type:	renamed attachment file

What is an ATTACHMENT file?

ATTACHMENT files mostly belong to Microsoft Outlook. Files with the ATTACHMENT extension are files that have been renamed to mark them as attachments from email or document exchanges. They can actually contain several common file types.
Examples include:

A JPEG image stored in the JFIF format. For more details, visit JPEG.org.

A document in PDF format meant to be viewed with Adobe Acrobat Reader.

An email message header generated by a program like Microsoft Outlook.

FilExt.com note: This renaming often happens to help systems manage attachments and may hide the file's original extension. To view the file correctly, you might need to change the suffix to .jpg for images, .pdf for documents, or open it with an email client if it contains header information.

How to open ATTACHMENT files

You need a suitable software like Microsoft Outlook to open an ATTACHMENT file. Without proper software you will receive a Windows message "How do you want to open this file?" or "Windows cannot open this file" or a similar Mac/iPhone/Android alert. If you cannot open your ATTACHMENT file correctly, try to right-click or long-press the file. Then click "Open with" and choose an application. You can also display a ATTACHMENT file directly in the browser:. Just drag the file onto this browser window and drop it.

Online ATTACHMENT Text Viewer

Choose your .attachment file to analyze

or drag and drop it here

Online File Viewer

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Programs that open and convert ATTACHMENT files:

Microsoft Outlook
See the previous paragraphs to learn more about the main application. ATTACHMENT files are often referred to as Microsoft Outlook miscs because this type of file is primarily created or used by this software.
Email clients (e.g., Microsoft Outlook)
The *.ATTACHMENT file extension is a generic naming convention used by email clients (such as Microsoft Outlook) and other software to denote files attached to an email message or other document. These files can be virtually any file type, such as images (JPEG), documents (PDF), or other data files. The .ATTACHMENT extension itself does not specify the underlying file format. It serves as a temporary name until the recipient downloads and restores the original file name and extension. Therefore, to determine the actual file type, one needs to examine the file's content or metadata after removing the .ATTACHMENT extension. This file format is classified as Generic file extension.

ATTACHMENT file format:

If you know the file format, you can also find out how to open or edit the file. The first characters in a file identify the file format, for example, HTML files start with the bytes <html>. File extension, signature and file format must match; otherwise errors will occur when the file is opened. When there is a problem with a file, the first step to solving it is to determine the file format. Our evaluation of the ATTACHMENT files looks like this:

ATTACHMENT is not that commonly used as a file extension. This file type includes different formats for the applicable programs. However, the following two file formats are common:

30% of all ATTACHMENT files are based on the popular JFIF file format. JFIF is short for JPEG File Interchange Format. It is a bitmap graphic that uses JPEG compression. The contents of these files cannot be read by a human; only a computer program can interpret the data. Most of these files are 240 KB to 1 MB in size. The file type was created recently. The files contain the following words: JFIF, acsp, desc, gXYZ, mntrRGB XYZ, @ICC_PROFILE and trXYZ. A usual file name is Attachment.. These files are often associated with resized.
15% of all ATTACHMENT files use the same file format, which can be identified by the letters "Re" at the beginning. These files are plain text, which means they can be viewed with any text editor such as Windows Editor, Nano for Linux, and TextEdit for macOS. A typical file size is 93 KB. The following keywords are characteristic: Received: from, with, Return-Path, LHLO, com, mail and LMTP. A usual file name is Attachment..

All other ATTACHMENT files (55%) have no consistent format, frequently e.g. PDF, ZIP, JSON, PNG and From. Drag & drop your file here to see the file format and a preview of your ATTACHMENT file!

Technical Data for ATTACHMENT File Extension

File classification:

Misc

Related files:

eml, msg, jfif, attachment-01, attachment-02, online, file, check, paint, mime-attachment, zip, rpmsg, jpg, jpeg, pdf, png

Mime type:

application/octet-stream

an attachment renamed attachment file is a special file format and should only be edited and saved with the appropriate software.

How to solve problems with ATTACHMENT files

Associate the ATTACHMENT file extension with the correct application.
Update your software that should actually open renamed attachment files. Because only the current version supports the latest ATTACHMENT file format. Search, therefore, e.g. on the manufacturer website after an available Microsoft Outlook update.
To make sure that your ATTACHMENT file is not corrupted or virus-infected, get the file again and scan it with Google's virustotal.com.
Click here to open your .ATTACHMENT file online - secure, fast, and no downloads needed.